• Proceedings of the Korea Water Resources Association Conference
• /
• 2006.05a
• /
• pp.467-471
• /
• 2006

At the current of the time, the ecologic stream is the most important concern of all the country. Daejeon metropolitan city performing the plan to secure the Daejeon cheon (stream) instream water as the 1st stage of the ecologic stream development plan for the Daejeon 3 main stream. During the performing the plan to secure the Daejeon cheon (stream) instream water, the water sources are decided to supply from Yudeng cheon and Daecheong Dam by the various water sources evaluation. For the investigation of flow and quality of instream water, I applicate the HEC-RAS and QUAL2EU. Instream water is proposed as the $10{\sim}30cm$ water depth and 2 degree water quality (lower the BOD 2.0 ppm) by the report of city. It is reasonable to the water depth objective, but the water quality objective is not reasonable because of the seasonal quality changes of supplied water. I suggest that the basin management plan include the non-point source elimination must comprised to the Daejeon ecologic stream project.

• Ecology and Resilient Infrastructure
• /
• v.2 no.1
• /
• pp.33-41
• /
• 2015

In this study, an optimal improvement method of stream channel structure is presented for the enhancement of fish habitat suitability by genetic algorithm. The correlation between fish habitat suitability and physical disturbance in stream is analyzed according to the changes of hydraulic characteristics by channel structure rehabilitation. Zacco koreanus which is an indicator fish of the soundness of aquatic ecosystem was selected as a restoration target species by investigating the community characteristics of fish fauna and river environments in Wonju stream. The habitat suitability is investigated by PHABSIM with the habitat suitability index of Zacco koreanus. Hydraulic analysis by HEC-RAS and physical disturbance evaluation in stream are carried out. The optimal channel width modified for the enhancement of fish habitat suitability is provided. The correlation analysis between habitat suitability and physical disturbance with the change of hydraulic characteristics by channel modification showed that the proper channel modification enhanced fish habitat suitability and mitigated physical disturbance in the stream. The improvement of physical disturbance score by the channel structure rehabilitation for the enhancement of fish habitat suitability was confirmed in this study.

• Spatial Information Research
• /
• v.11 no.2
• /
• pp.143-153
• /
• 2003

In order to investigate the effect of a pouring rain that it follows in the typhoon, the effect analysis with actual measurement data of rainfall outflow it follows in flood basin is necessary. Also there is a case that it analyzes with the fact that the rainfall occurs identically in whole basin in case of the rainfall outflow analysis, but the actual rainfall distribution from the basin very will be irregular and the interpretation which it reflects must become accomplished. It created spatial information of terrain, land use and the soil using GIS. It created topographical factor of the subject area and calculated CN(runoff curve number) with WMS(Watershed Modeling System). It calculated runoff using a HEC-1 model and the Rational Method connected at the WMS. By connecting GIS and WMS, it calculated the effect of a pouring rain and runoff from the construction area. Also it will be able to apply with a basic data in more efficient runoff analysis.

• Journal of Korea Water Resources Association
• /
• v.55 no.10
• /
• pp.737-748
• /
• 2022

Due to the lack of flood data, the water engineering practice calculates the design flood using rainfall frequency analysis and rainfall-runoff model. However, the rainfall frequency analysis for arbitrary duration does not reflect the regional characteristics of the duration and amount of storm event. This study proposed a practical method to calculate the design flood in a watershed considering the characteristics of storm event, based on the bivariate rainfall frequency analysis. After extracting independent storm events for the Pyeongchang River basin and the upper Namhangang River basin, we performed the bivariate rainfall frequency analysis to determine the design storm events of various return periods, and calculated the design floods using the HEC-1 model. We compared the design floods based on the bivariate rainfall frequency analysis (DF_BRFA) with those estimated by the flood frequency analysis (DF_FFA), and those estimated by the HEC-1 with the univariate rainfall frequency analysis (DF_URFA). In the case of the Pyeongchang River basin, except for the 100-year flood, the average error of the DF_BRFA was 11.6%, which was the closest to the DF_FFA. In the case of the Namhangang River basin, the average error of the DF_BRFA was about 10%, which was the most similar to the DF_FFA. As the return period increased, the DF_URFA was calculated to be much larger than the DF_FFA, whereas the BRFA produced smaller average error in the design flood than the URFA. When the proposed method is used to calculate design flood in an ungauged watershed, it is expected that the estimated design flood might be close to the actual DF_FFA. Thus, the design of the hydrological structures and water resource plans can be carried out economically and reasonably.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.3B
• /
• pp.291-300
• /
• 2006

In this study a statistical water quality monitoring network design of Kyung-An stream is proposed. Water quality data for the design is obtained by QUAL2E model simulation. The observed monthly average water quality data from March to November in Kyung-An stream has been applied to this study. HEC-RAS model is also used for QUAL2E hydrauric parameter estimation. Before QUAL2E water quality parameter estimation, FORA is performed to reduce the number of parameters to be estimated, and then water quality parameters are calibrated with a observed monthly average data. Using these simulated water quality data, the number of gage station and its location are estimated by kriging theory and branch & boundary method. Such a network design is based on two case; average flow and low flow case, respectively. Next, proportional sampling method is applied to estimate the sampling frequency.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2009.05a
• /
• pp.2004-2008
• /
• 2009

최근 하천오염에 대한 중요성이 크게 대두되고 있으며, 하천 오염을 방지하기 위한 다양한 방법이 강구되고 있다. 이러한 하천 오염방지를 위한 노력의 일환으로 4대강 수계에 대한 수질오염총량제를 실시하고 있다. 수질오염초량제에 있어 중요한 것은 현재 하천의 상태 및 장래 하천의 상황 즉, 수질 상태를 파악하는 것이 중요하다. 이러한 현재 및 미래의 하천 수질 상태를 파악하기 위해 수질 모델링이 필요하다. 본 연구에서는 수질오염총량제를 시행하고 있는 탐진강유역을 연구 대상으로 선정하였다. 대상 하천수질을 모의하기 위한 모형 중에 가장 보편적이고 광범위하게 사용하고 있는 US EPA에서 개발한 Water Quality model 중에 Qual2E 모형의 단점을 보완하여 개발된 Excel기반의 후속모델 Qual2K를 이용하였다. 모형의 적용은 탐진강 유역을 두 개의 단위유역으로 나누어 한 개의 단위유역을 1개의 Reach로 설정하여 총 2개의 Reach를 형성하였다. 탐진호를 Head water로 설정하고 본류23km를 중심으로 유입되는 지천을 소구역의 점 오염원으로 간주하여 적용하였다. 모형의 반응계수는 실측자료를 사용하여 시행착오법에 의해 검토..보정하였으며, 수리입력계수의 산정은 HEC-RAS모형을 사용하여 수심-유량계수와 유속-유량계수를 산정하였다. 수질모의 항목은 실측자료 2007년 배출부하량을 바탕으로 하여, 수질오염총량제의 수질관리 기준인 BOD와 부영양화 물질 T-P로 정하였다. 검정자료와 보정자료는 2007년 수질관측소의 실측자료를 사용하였다. 유량조건은 하천수질환경기준의 설정근거인 저수량(Q275)을 기준으로 탐진강 유역의 수질을 모의 하였다. 그 결과 Qual2K를 이용해 탐진강 수질 모의 결과 검 보정에서 양호한 결과를 나타냈다.

• Journal of Korea Water Resources Association
• /
• v.38 no.2
• /
• pp.97-110
• /
• 2005

This paper presents a procedure of evaluation of reservoir capacity for additional water storage for dam rehabilitation. One of the techniques on the extension of rainfall has been developed, and the daily stream flows were simulated by the NWS-PC long-term rainfall-runoff model with the input of the extended daily rainfall which was stochastically generated by the nonhomogeneous markov chain model. We peformed a reliability analysis to Guisan dam about the optimal capacity of dam rehabilitation by using performance criteria that Hashimoto et al. (1982) presented. We estimated that the most suitable water level is approximately 155EL.M. suggested that this method can use supplemental methods to estimate optimum dam scale.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.7 no.5
• /
• pp.179-186
• /
• 2007

This paper has investigated a rise of water level in upstream and downstream of bridge, which is caused by accumulation of debris in a bridge. The debris has been classified into several types in terms of size. The rise of water level which has been caused by installation and removal of sheet pile that is used to block water in a bridge has been analyzed using HEC-RAS model. According to the analysis, it has turned out that the debris has no influence on the rise of water level in ordinary water flow. In addition, sheet pile has little impact on the rise of water as well. Even though the impact of sheet file has turned out trivial in flood flow just like the ordinary water flow, it's been simulated that the maximum water level difference between upstream and downstream of bridge turned out more than 1.0meter because of debris in 80-year or more flood frequency. When the rise of water level in upstream from the cross section of the bridge was investigated based on 100-year flood frequency, besides, it has turned out that it had an influence up to 17.84km distance because of the effect of debris.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2009.05a
• /
• pp.42-46
• /
• 2009

최근 국지적 집중호우로 인한 인명과 재산피해가 증가하고 있는 실정이며 이러한 피해를 경감하기 위한 하나의 방책으로써 홍수예경보 시스템 구축의 관심이 늘어나고 있다. 그러나, 기존의 홍수예측 시스템은 강우관측치를 모형의 입력 자료로 홍수유출을 계산하는데, 집중호우와 같은 악기상 조건에서는 관측강우자료를 이용한 유출해석 결과를 이용하여 홍수예경보 시스템을 운영할 경우 예방 대응시간의 부족으로 인해 방재 효율성이 떨어지는 한계성을 지니고 있다. 이와 같은 상황에서 정확한 기상예보를 활용한 기상-수자원 연계기법을 개발하여 홍수예경보 시스템에 적용한다면 악기상 감시예측기술의 향상과 더불어 재해의 방지차원에서 매우 유용한 대책이 될 뿐만 아니라 그 활용성을 극대화 시킨다면 수자원분야의 치수기 홍수예측 등에 매우 유용하게 활용될 수 것이다. 이에 본 연구에서는 모형의 입력으로 활용되는 단기 예측강우의 국내 적용성 여부를 검토하기 위해 30km의 공간해상도를 가진 단기지역예보모델인 RDAPS(Regional Data Assimilation and Prediction System) 예측강우 자료에 대하여 수문학적 정확도 분석을 수행하였으며, 예측강우의 정확도 향상을 위한 편차보정 방법을 개발 적용하였다. 또한 산정된 예측강우를 바탕으로 HEC-1 모델과의 연계방안을 제안하고 이를 이용하여 한강수계 주요 댐유역의 예측유입량을 산정, 댐 운영에 대한 적용성을 판단하고자 한다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2008.05a
• /
• pp.1589-1593
• /
• 2008

하천의 골재는 도로, 항만, 주택건설 등 다양한 건설재료로 이용되어 왔으며 급속한 산업화와 더불어 국가건설사업, 지방자치단체의 수익사업으로 인해 골재 수요가 급격히 증가해 왔다. 그러나 체계적인 조사 및 연구가 없이 무분별하게 행해진 하천준설은 하상저하, 하천의 불안정, 하상의 장갑화 등 물리적 영향뿐만 아니라 주변 하천의 식생, 저서생물의 서식처 등 수서생태계의 파괴, 하천정화능력 저하, 교각의 노출 등 생물적 경제적인 측면에서 악영향을 미치고 있다. 본 연구에서는 하천준설사업이 꾸준히 진행 중에 있는 감천을 연구대상지역으로 선정하여, 1차원 수치모형인 Hec-ras4.0을 이용하여 준설량에 따른 흐름특성 및 교란된 하천의 적응과정을 분석하였다. 지형자료는 수치지도 및 실측자료를 토대로 하여 구축하였으며 장 단기 하상변동을 모의해 비교 분석하였다. 그 결과, 준설구간의 흐름특성은 준설전에 비해 수위가 감소되었고 하상변동은 준설구간의 상류부에서는 하상저하가 발생하였으며 하류부에서는 하상상승이 발생되었다. 본 연구의 결과는 하천준설에 따른 하천환경 및 물리적 영향을 최소화하고, 하천공사 실시와 수공구조물의 설계 및 유지관리 등에도 활용될 수 있을 것이다.